Pneumatic tires of open center, hollow toroidal construction are well known to every automobile tire customer. These tires are generally horseshoe-shaped in cross-section and employ two axially spaced apart circular beads located at the radially inner limits of the sidewalls to effect sealing engagement with the wheel mounting rim. The rim is of relatively thin sheet metal and a conventional valve stem is sealingly anchored in a central hole therethrough to allow pressurized air to be delivered to, or removed from the internal chamber of the tire. An example of this conventional tire construction is disclosed in U.S. Pat. No. 3,804,141 issued Apr. 16, 1974 to F. Huttner.
However, the sealing problems associated with the installation of a fully oval pneumatic tube-tire on a supporting rim are entirely different. For one thing these oval tires do not have circular beads for sealing engagement radially against the rim seats and axially against the radially extending peripheral flanges. For another, these oval tires have a generally flat or gently axially arcuate radially inner base which is supported by a rim of corresponding minimal contour. Exemplifying these distinctions are the various oval and rim configurations disclosed in U.S. Pat. No. 3,606,921 issued Sept. 21, 1971 to C. E. Grawey, and assigned to the assignee of the present invention.
Heretofore, as far as is known, valve stems have been effectively constructed as only an integral part of these tubeless oval tires. Typically, an insert having an integral valve stem or threaded valve stem fitting is vulcanizably molded into the base of the tire as a part of the manufacturing process. This is a relatively costly manufacturing step, and the inert usually protrudes radially inward so that it undesirably affects the assembly procedure for installing the tire on the rim. Then too, proper caution must be taken to precisely radially align the valve stem with the valve opening through the rim during the assembly of the oval tire.
If, on the other hand, an inlet passage in the base of the oval tire is aligned with a valve opening in the rim, and a valve stem is subsequently installed sealingly solely in the opening, the manufacture and installation of the tire would be a much simpler and more economical procedure. While this advantageously permits a conventional automobile tire valve stem to be used which would be serviceable independently of the tire, it raises the primary problem of a potential air leakage path through the unsealed air inlet passage and outwardly between the base of the oval tire and the supporting rim. Particularly, circumferential leakage becomes a major consideration when split rims or multi-sectional rims are utilized because air may escape at any gap therebetween. With these sealing problems solved, an economical and effective valve stem entry zone can be provided.